In reference to pipe handling tools used in the drilling industry, there are those generally referred to as ‘pipe tongs’ or ‘casing tongs’. Many of these are fully or semi automated units and are specific to the oil and gas drilling industry, and not within the scope of the present invention. Prior art tools relating to the present invention are more accurately described as ‘manual tongs’, ‘chain tongs’, ‘Petol tongs’, ‘BV tongs’, ‘Rapspan tong’, ‘pipe wrench’, or ‘stilson’, and are identified by having a handle, or lever, which serves to permit load being applied by hand, and, if so designed, also permitting the application of mechanical force to that lever.
Prior art tools rely heavily on the casting, forging, machining, and heat treatment processes as necessary to achieve the least practicable weight with the highest possible strength/torque/load capacity, since weight is a critical safety factor when large tools are to be man-handled, such as on waterwell and exploration mobile drillrigs. It has been common for several decades for manufacturers of these drills to fit as standard equipment an adjustable pipe wrench, modified by cutting the handle short, welding a lug to the shortened handle for attachment to a hydraulic cylinder, for the purpose of applying high torque to the drillpipe and drilling tools. Although relatively lightweight and easy to use, it is an inappropriate modification of a hand tool, and has become the accepted norm within the industry, notwithstanding the well documented injuries resulting from this unsafe practice.
These types of breakages are without warning as the component, whether faulty or overloaded, suddenly fails and the tool flies apart, severely injuring any body in its path. U.S. Pat. No. 6,119,558 seeks to minimise these injuries by the addition of a safety device in the case of such failures.
A well known and regarded tool is manufactured by Petol Tool Co, but this tool also is not without its problems in that it is cumbersome to man-handle, and heavily reliant on expensive manufacturing techniques.
U.S. Pat. No. 5,957,010 seeks to alleviate the downside of the Petol wrench by making a somewhat lighter but equally strong tool, at a lower cost. Although achieving this to a degree, in today's ever-cost conscious environment, it is still considered an expensive tool, due mainly to the extensive machining required in its manufacture.